1. Field of the Invention
The present invention relates to a cushion, and more particularly to a cushion for a backrest of a chair.
2. Description of the Related Art
A conventional cushion for a backrest of a chair in accordance with the prior art shown in FIG. 9 comprises a curved main body 50 having a first end formed with a fixed portion 51 and a second end formed with a movable portion 52, an adjusting device 53 mounted on the fixed portion 51 of the main body 50, and a guide wire 54 having a first end connected to the movable portion 52 of the main body 50 and a second end connected to the adjusting device 53. Thus, the guide wire 54 is driven and moved by operation of the adjusting device 53 to pull or release the movable portion 52 of the main body 50 so as to adjust the curvature of the main body 50.
However, the curvature of the main body 50 is changed by operation of the adjusting device 53, so that the curvature of the main body 50 cannot be adjusted automatically, thereby causing inconvenience to a user in adjustment of the curvature of the cushion.